This invention relates to a method and apparatus for reducing adhesive build-up on ultrasonic bonding surfaces through the application of a fluid to at least a portion of the ultrasonic bonding surfaces. More specifically, this invention relates to a method and apparatus for reducing adhesive build-up on ultrasonic bonding surfaces that alleviates heat build-up in the ultrasonic bonding equipment and reduces manufacturing downtime for cleaning and equipment repair and/or replacement.
Absorbent articles, including diapers, training pants, adult incontinence products and feminine care pads, are generally manufactured by combining a liquid-permeable topsheet; a liquid-impermeable backsheet attached to the topsheet; and an absorbent core disposed between the topsheet and the backsheet. The topsheet, backsheet, absorbent core, and other components of the absorbent article or product may be coextensive or non-coextensive depending on the requirements of the product. Generally, each of the individual components is arranged so that it has intimate contact along at least a portion of its boundary with at least one other adjacent component of the absorbent article. Typically, each component is connected to an adjacent component of the absorbent article by a suitable bonding and/or fiber entanglement mechanism, such as ultrasonic or adhesive bonding, mechanical or hydraulic needling or other means generally known in the art. Often, both adhesive bonding and ultrasonic bonding are utilized in the manufacture of absorbent articles.
If adhesive is used to attach a portion of one component to a portion of another component to form a composite, the adhesive may be exposed to ultrasonic energy in subsequent processing steps. The ultrasonic energy may cause the adhesive to flow. This, in turn, may lead to build-up or accretion of the adhesive on the ultrasonic bonding horn and/or anvil if the adhesive penetrates through some or all of the composite, seeps between the separate layers of the composite, or both. Often this build-up, over time, results in uneven bonding and increased heat build-up on the ultrasonic bonding horn. Furthermore, the adhesive build-up often leads to horn failure and increased down time of the production machine for maintenance and/or cleaning.
Now, a method and apparatus for substantially reducing the amount of adhesive build-up or accretion on ultrasonic bonding surfaces has been developed. Intermittently or continuously applying a fluid to the ultrasonic bonding surfaces prevents or alleviates the build-up or accretion of adhesive on the surfaces by impeding adhesion of adhesive material to the ultrasonic bonding surface. By reducing the amount of adhesive build-up on the ultrasonic bonding surfaces bond integrity is maintained and downtime due to system failures and/or cleaning are reduced.
Briefly, this invention relates to a method and apparatus for reducing adhesive build-up on ultrasonic bonding surfaces during the operation of an ultrasonic bonding system. Accordingly, one version of this invention is directed to a method for reducing adhesive build-up on ultrasonic bonding surfaces comprising the steps of: providing an ultrasonic bonding surface; providing a pad proximate to, and in fluid contact with, the ultrasonic bonding surface; providing a fluid; and conducting the fluid to the pad so that the fluid is intermittently or continuously applied to at least a portion of the ultrasonic bonding surface. In some versions of the present invention the ultrasonic bonding surface is the ultrasonic bonding surface of an ultrasonic bonding horn. In other versions, the ultrasonic bonding surface is the ultrasonic bonding surface of an ultrasonic bonding anvil.
Another version of a method for reducing adhesive build-up on ultrasonic bonding surface comprises the steps of: providing an ultrasonic bonding surface; providing a pad having a width dimension equal to the width dimension of the ultrasonic bonding surface, proximate to, and in fluid contact with, the ultrasonic bonding surface; providing a fluid; and conducting the fluid to the pad so that the fluid is intermittently or continuously applied to at least a portion of the ultrasonic bonding surface.
In another aspect, a method for reducing adhesive build-up on ultrasonic bonding surfaces comprises the steps of: providing an ultrasonic bonding surface; providing a pad in a position above, and proximate to, the ultrasonic bonding surface such that the lower surface of the pad is in fluid contact with the ultrasonic bonding surface; providing a fluid; and conducting the fluid to the pad so that the fluid is applied intermittently or continuously to at least a portion of the ultrasonic bonding surface.
In another aspect, a method for reducing adhesive build-up on ultrasonic bonding surfaces comprises the steps described in any of the proceeding three paragraphs with the additional step of providing a pad comprised of a sponge material.
For example, a method for reducing adhesive build-up on ultrasonic bonding surfaces having features of the present invention includes the steps of: providing an ultrasonic bonding surface; providing a pad comprised of a cellulosic sponge material, polyurethane foam material, or natural sponge material proximate to, and in fluid contact with, the ultrasonic bonding surface; providing a fluid; and conducting the fluid to pad such that the fluid is intermittently or continuously applied to at least a portion of the ultrasonic bonding surface.
Another version of a method for reducing adhesive build-up on ultrasonic bonding surfaces of the present invention comprises the steps of: providing an ultrasonic bonding surface; providing a pad proximate to, and in fluid contact with, the ultrasonic bonding surface; providing a fluid; conducting the fluid to the pad in a quantity sufficient to place the pad in a substantially saturated condition; and conducting the fluid to the pad at a rate sufficient to maintain the pad in a saturated condition such that the fluid is continuously applied to at least a portion of the ultrasonic bonding surface.
In another version, a method for reducing adhesive build-up on ultrasonic bonding surfaces of the present invention comprises the steps of: providing an ultrasonic bonding surface; providing a pad on a roller proximate to, and in fluid contact with, the ultrasonic bonding surface; providing a fluid reservoir; providing a fluid; and conducting the fluid to the pad so that the fluid is continuously applied to at least a portion of the ultrasonic bonding surface. In some embodiments of the invention, the pad is provided in fluid contact with the ultrasonic bonding surface of an ultrasonic bonding horn and in others the pad is provided in fluid contact with ultrasonic bonding surface an ultrasonic bonding anvil.
In another aspect, a method for reducing adhesive build-up on ultrasonic bonding surfaces comprises the steps of: providing a ultrasonic bonding surface; providing pad on a roller proximate to, and in fluid contact with, the ultrasonic bonding surface; providing a fluid reservoir; providing a fluid; and conducting the fluid to the pad so that the fluid is continuously applied to substantially all of the ultrasonic bonding surface.
A further version of a method for reducing adhesive build-up on ultrasonic bonding surfaces of the present invention comprises the steps of: providing an ultrasonic bonding surface; providing a pad on a roller proximate to, and in fluid contact with the ultrasonic bonding surface; providing a fluid; providing a fluid reservoir at a height sufficient to allow the fluid to be conducted by gravity to the pad; and conducting the fluid to the pad so that the fluid is continuously applied to at least a portion of the ultrasonic bonding surface.
Another version of a method for reducing adhesive build-up on ultrasonic bonding surfaces of the present invention comprising the steps of: providing an ultrasonic bonding surface; providing a pad on a roller proximate to, and in fluid contact with the ultrasonic bonding surface; providing a fluid reservoir; providing a fluid; providing a pump to conduct fluid to the pad; and conducting the fluid from the reservoir to the pad so that the fluid is continuously applied to at least a portion of the ultrasonic bonding surface.
In another aspect, a method having the features of the present invention comprises the steps in any of the three preceding paragraphs, with the additional step of selecting a fluid wherein the fluid is water, propylene carbonate, isopropyl alcohol, mineral oil, 0.25 w/w % aqueous solution of an anionic surfactant, or any combination thereof.
For example, a method for reducing adhesive build-up on ultrasonic bonding surfaces of the present invention comprising the steps of: providing an ultrasonic bonding surface; providing a pad on a roller proximate to, and in fluid contact with, the ultrasonic bonding surface; providing a fluid reservoir; providing mineral oil; and conducting the mineral oil to the pad so that the mineral oil is continuously applied to at least a portion of the ultrasonic bonding surface.
Another version of a method for reducing adhesive build-up on ultrasonic bonding surfaces of the present invention comprises the steps of: providing an ultrasonic bonding surface; providing a hollow, cylindrical polyurethane open-cell foam pad having interior and exterior surfaces; providing a roller mount proximate to the ultrasonic bonding surface; providing the pad on the roller mount such that the exterior surface of the pad is in fluid contact with the ultrasonic bonding surface; providing a fluid reservoir; providing mineral oil; providing a pump; delivering the mineral oil to the interior surface of the pad at a rate of at least about 3 milliliters per minute; and conducting the mineral oil to the exterior surface of the pad so that the mineral oil is continuously applied to substantially all of the ultrasonic bonding surface. In some versions, the ultrasonic bonding surface is the ultrasonic bonding surface of an ultrasonic bonding anvil. In other versions, the ultrasonic bonding surface is the ultrasonic bonding surface of an ultrasonic bonding horn.
One version of an apparatus having features of the present invention comprises: an ultrasonic bonding anvil and an ultrasonic bonding horn, both the anvil and the horn each comprising an ultrasonic bonding surface; at least one application element (e.g. a pad, sponge, or other application element), proximate to and in fluid contact with the ultrasonic bonding surface of the anvil or the horn, the application element being capable of applying fluid to at least a portion of the ultrasonic bonding surface(s); a reservoir for containing the fluid, the reservoir having an outlet; a tube, pipe, or other conveyance element having one end attached to the outlet and the other end proximate to, or connected with, the application element such that the fluid conveyed from the reservoir via the conveyance element is discharged to the application element; and, optionally, a conduction element (e.g. a pump) interposed between the fluid reservoir and the application element capable of providing a motive force for moving the fluid from the reservoir, and via the conveyance element, to the application element. A conduction element may not be necessary when the force of gravity provides a sufficient motive force for moving the fluid from the reservoir to the application element. In some versions of the invention the volumetric flow rate or mass flow rate of the fluid may be controlled by pump speed or other variable associated with operating the pump. Alternatively, when the force of gravity provides a sufficient motive force for moving the fluid from the reservoir to the application element, a valve or other mechanical element may be used to regulate the volumetric flow rate or mass flow rate of the fluid from the reservoir to the application element.
These and other features, aspects, and advantages of the present invention will become better understood with regard to the following description, appended claims, and accompanying drawings.